Research Disclosure, Vol 228, April 1983, Item 22843, discloses overall bleaches for reducing the density of dye image prints produced by transferring dye from separation positives. Three specifically identified overall bleaching agents are 1,4-phenylenedimethylbis(2,2'-iminodiethanol) dihydrochloride, N-benzyl-N-tri(2-hydroxyethyl) ammonium chloride, and 1,4-phenylene bis[methyltri(2-hydroxyethyl)ammonium chloride]. Research Disclosure is a publication of Kenneth Mason Publications Limited; Emsworth; Hampshire P010 7DD; United Kingdom.
The use of ferric complexes of polycarboxylic acids to bleach silver from processed silver halide photographic elements is well known in the art. The use of such complexes, optionally with concurrent fixing of silver halide, is illustrated by U.S. Pat. Nos. 3,615,508, 3,770,437, 3,870,520, 4,242,442, and 4,288,618. These patents teach that ferric complexes of polycarboxylic acids are recognized to be environmentally preferable to ferric cyanide bleaches, but suffer from a limited oxidation capability, which is manifested by limited bleaching capacity and in some instances by leaving imaging dyes in a less than fully oxidized leuco form.
Research Disclosure, Vol. 225, January 1983, Item 22534 discloses spectrally sensitized high aspect ratio tabular grain emulsions to be advantageous in silver halide photographic elements. It is well known in the art that spectral sensitizing dyes are effective by reason of being adsorbed to silver halide surfaces and that a substantially optimum level of spectral sensitizing dye is a function of the available silver halide surface area. Generally spectral sensitizing dye concentrations are specified in terms of a percentage of a monomolecular dye layer coverage of the silver halide surface area available. Because of the high ratio of surface area to volume of high aspect ratio tabular grains, high ratios of spectral sensitizing dye to silver halide can be present.